The present invention relates to a combined molding and assembling apparatus used for the production of products utilizing resin molded articles.
According to a conventional practice to make a product utilizing a resin molded article, it is a long-standing way to manufacture a planned number of resin molded articles which are, after having been allowed to stand for a certain period of time, transferred to an assembling site for the fabrication into products. This is rather a universal method because of the following reasons:
(A) The resin molded article is susceptible to shrinkage after the molding and, therefore, it is an accepted policy to allow the resin molded article to stand for more than 24 hours for aging.
(B) The supply of the resin molded article to the assembling site after it has been examined as to the dimension requirement should not be done before the passage of more than 24 hours.
(C) While the molding machine is usually run day and night, continuously repeating a cycle of molding operation in a predetermined sequence, the assembling work requires the intervention of manual labors and, therefore, tends to take a different time from one assembling site to another by some reason particularly where the assembling sites are lined up to permit a product to be sequentially fabricated. In addition, the working hour during which assembling workers have to do their job is limited to 7 to hours excluding the lunch time.
(D) Since the molding machine has numerous drives usually comprised of hydraulic cylinders and associated hydraulic circuits, the molding machine tends to be easily contaminated with oil stains and is, therefore, desired not to be used in a clear working area.
(E) Since the molding machine is relatively bulky in size, it will bring about a problem with the layout of the apparatus as a whole where the assembling job is to be performed on a linear conveyor system.
However, with the recent change in production situation, it has now become considered disadvantageous to perform the molding and the assembly at separate sites spaced a considerable distance from each other. More specifically, the recent change in production situation is such that the age of limited production of a diversity of planned design of products has superseded the age of mass production of a single planned design of products and that both the increase in wage as a result of the improved mode of life and the improvement in production technology has made the direct cost, incurred in processing and assembling, approach the balance in cost indirectly incurred in a workshop.
The change in production situation has in turn brought about the following problems:
(i) Since the parts are diversified in design, the stockpile is increased.
(ii) The increased stockpile has increased the importance of stock control, the necessity of quality control, the necessity of sorting procedure, the necessity of assembling rehearsal, and the weight of other non-mechanized jobs, constituting a cause of the increased manufacturing cost combined with increased personnel expenses.
(iii) While the mold assembly of the molding machine has been provided with a capability of making a plurality of molded articles in each cycle of operation of the machine, the number of molded articles to be made using the same mold assembly is decreased because of the decrease in production per lot and also because of the decrease in stockpile of semi-manufactured products, and the increase in frequency of replacement of the mold assembly as well as material has become observed. Therefore, the machine has no longer been able to exhibit its performance.
Because of the reasons stated above, the adequacy to carry out the molding and the assembly at spaced apart sites has come to lack its foundation.
In addition thereto, the prior art assembling conveyor system has the following problems. Before the problems are discussed, the structure of the prior art assembling conveyor system will be described with reference to FIG. 1 of the accompanying drawings.
The assembling conveyor system shown in FIG. 1 is used on a production line for fabricating mechanisms of an electric appliance such as an audio tape recorder or a video tape recorder. The system comprises a bench 1 having a foot rest 12, a chain conveyor 2 having its upper run movable in a direction shown by the arrow, a pallet 3 movable together with the conveyor 2, a pawl 4 of a catch mechanism for causing the pallet 3 to slip relative to the conveyor 2, a work 5 positioned on the pallet and onto which a resin component is to be fabricated, a parts feeder 6 for successively supplying resin components while imparting a vibration thereto, an alignment chute 7 for aligning the resin components, which have been supplied from the parts feeder, in a row within the reach of an attendant worker who would be sitting on a chair or stool 11 shown by the phantom line, a drive shaft 8 for transmitting a drive from a motor (not shown) to the chain conveyor 2, a control box 9 having a plurality of operating buttons 10, and levelling jacks 13 through which the bench 1 is installed on a floor or ground surface.
If a plurality of the systems of the above described construction are lined up, the pallet will move one system to the next adjacent system, travelling from one end to the opposite end of the assembly line. The pallet so moved can be brought to a halt at a working site occupied by the attendant worker at which time the pawl 4 of the catch mechanism has projected into a space, in which the pallet moves, for engagement with the pallet allowing the latter to slip relative to the conveyor 2. Then, the attendant worker picks up a resin component out from the alignment chute 7 and fabricates it onto the work 5 resting on the pallet 3. When a switch on the control box 10 is thereafter operated, the pawl 4 of the catch mechanism is temporarily retracted to release the pallet 3, allowing the latter to be transported by the conveyor 2 in the direction indicated by the arrow. The pawl 4 once retracted returns to the original, projected position in readiness for the subsequently transported, next succeeding pallet.
The above described assembling conveyor system can be combined not only with the parts feeder, but also with one or more of a press, a screw fastening machine, a welding machine and a bonding machine. However, so far as the fabrication of the resin components onto the works is concerned, two alternative methods are possible; to use the assembling conveyor equipped with the parts feeder and to use the assembling conveyor with no parts feeder, but with a separate storage box full of the resin components.
However, as hereinbefore discussed, under the circumstances in which the wage is increasing and automated machinery such as industrial robots is also being introduced, the automation of the above described fabrication requires the system to be essentially equipped with the parts feeder 6 including the alignment device 7, and so is the prior art system devised. The problem with the prior art system is that, since the resin components being many in type have a complicated shape and are hard to be aligned and uniformly positioned, it is nearly impossible to control the position of each of the resin components prior to being fabricated onto the work. Although at present a study is being made to develop an industrial robot having an electronic eye-hand coordination system and, therefore, capable of correcting the position of the resin component after the discrimination of the shape and position of such resin component, it appears that, no matter how complete the robot may be, it would not be able to handle the resin components because most of the resin components are colored in monochrome and have a contour hard to be discriminated. Thus, at present, no one can rely on the robot engineering for the automated fabrication of products.